Ball point reservoir



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F. R. WITTNEBERT ET AL BALL POINT RESERVOIR Filed Aug. 23, 1966Frederick M'fneberf Ray A. Law/0n .la/m J. Dyson United States PatentOiice 3,416,869 Patented Dec. 17, 1968 3,416,869 BALL POINT RESERVOIRFrederick R. Wittnebrt, Whitewater, Ray A. Lawton,

Milton, and John Il. Dyson, Janesville, Wis., assignors to The ParkerPen Company, Janesville, Wis., a corporation of Wisconsin Filed Aug. 23,1966, Ser. No. 574,356 8 Claims. (Cl. 401--209) ABSTRACT F THEDISCLOSURE A ball point pen reservoir comprises a ball point writingtip, a tube connected to the tip and an insert disposed in the tube andcooperating with the inner wall of the tube to form a continuous,serpentine capillary passageway extending from the writing tip to alocation near the rear end of the tube for the ink contained in thereservoir. The insert comprises a series of generally circular wallswhich are interconnected by a series of longitudinally extending spacerwalls. Each circular wall includes an aperture located adjacent one sideof the two adjacent spacer walls, which extend from opposite sides ofthe circular wall.

The present invention relates in general to reservoirs lfor ball pointpens, and it relates more particularly to Ia capillary reservoir whichhas a large ink capacity relative to the overall length of thereservoir.

The very early ball point pens lutilized a relatively large -diametertubular reservoir having sealing means at the rearward end thereof forpreventing the ink from flowing out of the reservoir when it was in ahorizontal or inverted position. These early reservoir constructions didnot operate satisfactorily under the conditions normally encountered bywriting instruments, and the first truly successful ball point penemployed what has become known as a capillary reservoir. This type ofreservoir has a sufficiently small cross-sectional area that even thoughthe rearward en-d is open to the atmosphere the ink remains in thereservoir irrespective of its orientation. Although this type ofreservoir had the disadvantage that a relatively long reservoir wasrequired in order to hold an adequate supply of ink, it did performsatisfactorily. In fact, the capillary reservoir is still in use tod-ayin most ball point pens.

In order to increase the ink capacity of a reservoir having apredetermined length which, of course, is limited by the size of thewriting instrument with which it is associated, various constructionswere made wherein a capillary passageway was arranged along a tortuouspath. It was also suggested that a large diameter, non-capillary tubemight support the ink which would be held in place by a follower memberdisposed at the rearward end of the ink column and movable along thetube as the ink was used up. Ball point pens of this general type arealso on the market at the present time and for the most part operatesatisfactorily. There are, however, certain problems inherentlyassociated with the non-capillary reservoir.

It would, therefore, be desirable to provide a ball pen reservoir whichobviates the need for `a follower to prevent the ink from leaking out ofthe rearward end of the reservoir and which has acapacity-to-overall-length ratio much greater than that heretoforeprovided with capillary reservoirs and comparable to that achieved withthe follower type reservoir. Elimination of the follower, andparticularly the so-called grease fol-lower will avoid manymanufacturing and operational problems.

Therefore, a principal object of the present invention is to provide anew and improved capillary type reservoir for a ball point pen.

Another object of the present invention is to provide a large capacityball point pen ink reservoir which eliminates the need for `a followerto maintain the continuity of the ink vein in t-he reservoir.

A further object of the present invention is to provide an insert memberwhich may be positioned Within a tube to provide a continuous capillarypassageway from one end of the insert to the other.

A still further object of the present invention is to provide an insertwhich may be placed into a tubular reservoir member to convert saidtubular member from a noncapillary to a capillary reservoir.

Briefly, the above and further objects are realized in accordance withthe present invention by providing a reservoir consisting of a tubular,imperforate member adapted to be connected at one end to a ball pointwriting tip and having an insert disposed therein and cooperating withthe inner wall of the tube to form a continuous, serpentine capillarypassageway extending from the writing tip to a location near the rearend of the tube. The insert is so constructed as to be moldable of ashape-retaining plastic material and to occupy a relatively smalloverall volumetric space in the tube. Preferably, the insert and theinner wall of the tube have low energy surfaces Which help to preventthe ink from traveling toward the rear end of the tube.

Further advt-antages and a better understanding of the present inventionmay be had by reference to the following detailed description taken inconnection with the accompanying drawings wherein:

FIGURE 1 is a plan view, partly in section and partly broken away, of aball point pen cartridge embodying the present invention and showing thecartridge in an inverted position;

FIGURE 2 is an isometric view of a portion of an insert used in theembodiment of FIG. 1;

FIGURE 3 is a cross-sectional view of FIG. 1, taken along the line 3 3thereof, assuming the entire -device to be shown therein;

FIGURE 4 is a diagrammatic View showing successive portions of theinsert of FIG. 2 and is -used to facilitate an understanding of theoperation of the present invention;

FIGURE 5 is a fragmentary, sectional view of another reservoir embodyingthe present invention;

FIGURE 6 is a fragmentary, sectional view of still another embodiment ofthe present invention; and

FIGURE 7 is a fragmentary sectional view of yet another embodiment ofthe present invention.

Referring now to the drawings, and particularly to FIG. 1 thereof, thereis shown a ball point pen cartridge 10 including a writing .tip assembly12 and a generally tubular ink reservoir 14 suitably connected togetheras, for example, by swaging. The writing tip assembly 12 is conventionaland includes va writing ball 16 rotatably mounted in a socket 18. A feedtube includes a narrow capillary bore 20 which forms a feed channel forconveying ink from the reservoir 14 to the socket 18 and the ball 16. Inthis embodiment of the invention the reservoir 14 is formed by acylindrical metallic shell 22 having a thin plastic layer or coating 24on the inner wall thereof and an insert 26 preferably molded of plasticand fitted into the plastic lined shell 22. As is described more fullyhereinafter, the insert 26 cooperates with the substantially cylindricalinner wall 28 of the shell coating 24 to provide a generally serpentinecapillary passageway extending from a location near the rear end of theshell 22 to the rear end of the feed channel 20. The size and shape ofthis serpentine passageway and the materials by which it is definedcooperate with the ink contained therein to maintain a continuous veinof ink extending from the rear surface of the ink to the socket 18 andthus to the ball 16.

In order to permit facile assembly of the insert 26 into theplastic-lined shell 22, the insert 26 is an integral, shape-retainingmember having an envelope which is complementary to the inner wall 28.The insert 26 may thus -be separately molded and inserted into theplasticlined shell 22.

Referring also to FIG. 2, it will be seen that the insert 26 comprises aplurality of mutually parallel disk-like wall sections 30 which lie inplanes transverse to the longitudinal axis of the insert and which areconnected together in spaced apart relationship by respective ones of aplurality of imperforate, radially directed wall sections 32. Adjacentones of the radial wall sections 32 are mutually displaced by an angleof 90-degrees and when considered in a direction from front to rear,succeeding ones of the radial wall sections 32 are displaced in acounterclockwise direction. The cut-outs and radial wall sections could,however, progress in a clockwise direction if desired.

Irrespective of the diection in which the cut-outs progress, theresulting structure provides a generally helical reservoir from whichsubstantially all of the ink drains out during writing with a minimumamount of residual ink remaining between the walls 30.

The spaces between adjacent ones of the transverse, circular wallsections 30 are interconnected by generally triangular cut-out portions34. The cut-outs 34 are defined by a pair of edges which intersect at anangle of 90-degrees and extend to the periphery of the transverse wallsection. These cut-outs extend from a location near but spaced from thecenter of the associated circular wall section 30 with one edge thereofadjacent to the next lower radial wall section 32 and one edge adjacentto the next rearward or upward radial wall section 32. As shown in FIG.1, the rear end of the insert 26 is formed by a transverse wall section30 and the front end is formed by a radial wall section 32a which isspaced from the rear end of the feed channel 20. It may thus be seenthat a serpentine passageway is provided which extends from the cut-out34 in the rearmost transverse wall section 30 through the space betweenthat transverse wall and the next succeeding transverse wall, around theradial wall and down through the next cut-out 34 into the space betweenthe next two transverse wall portions, around the next radial wallportion into the next cut-out 34, etc. In order to eliminate highcapillary corners, it is preferable that all corners be iilleted.

Referring to FIG. 4, FIG. 4A is a view looking at the rear end of theinsert 26 and shows the rearmost transverse wall 30 wherein the cut-out34 extends from approximately O-degree to 270-degrees, one edge beingcoextensive with the right wall of the rearmost radial wall section 32.FIG. 4B shows the next succeeding transverse wall section 30 wherein thecut-out 34 extends from approximately l80-degrees to approximately270-degrees between the left-hand side of the rearmost radial wallsection 32 and the downward side of the next succeeding radial Wallsection 32. Ink travels along the top surface of this wall 30 in thedirection of the arrow.

FIG. 4C is a view looking toward the upper side of the third from therearmost transverse wall section 30 and shows the cut-out 34 extendingfrom approximately 90degrees to approximately ISO-degrees between theupper and left-hand sides, respectively, of the two adjacent radial wallsections 32. The arrow shows the direction of ink ow which iscounterclockwise.

FIG. 4D is a view of the fourth from the rearmost wall section 30 andshows the cut-out 34 located between -degree and 90degrees with thearrow indicating that the ink ows in a counterclockwise direction alongthe rear surface of this wall 30.

FIG. 4E shows the fifth from the rearmost transverse p wall section 30to be the same as the rearmost wall section of FIG. 4A, i.e., thecut-out 34 extends from O-degree to approximately 270-degrees. Theorientation of the next succeeding transverse wall sections and radialwall sections continue in the same sequence as indicated by FIGS. 4Athrough E, inclusive.

In order to provide the necessary rigidity to permit insertion of theinsert 26 into tight fitting relationship with the inner wall 28 of theshell, the radial wall sections 32 overlap by a dimension equal to thethickness of the wall sections 32 to provide an insert having a rodlikecentral core which is square in cross section and supports thecompressive load exerted on the insert during the insertion operation.

It is common practice to taper the forward end of a ball point reservoirand the reservoir 14 is constructed in this known manner. Consequently,the forward portion of the insert 26 and more particularly the wallportions 30 and 32 at the forward portion thereof define an envelopewhich is complementary to the taper of the surface 28 at the forward endof the shell. Moreover, the front end of the insert 26 terminates in aradial wall section which is spaced from the rear end of the feedchannel 2t) so that ink may feed from the reservoir into the feedchannel.

To eliminate the possibility of ink moving rearwardly in the reservoirunder the force of gravity or because of capillary creep, it ispreferred that the insert 26 be formed of a material having a low energysurface such, for example, as T eon, or that the insert be formed ofsome other material and coated with a low energy surface material.Likewise, it is preferred that the inner wall 28 have a low energysurface and in the embodiment shown in FIG. l this is accomplished bycoating the inner wall of the metallic shell 22 with a low surfaceenergy material 24.

In the embodiment of FIG. l, the shell 22 is formed of metal lined witha plastic layer 24. If desired, and as shown in FIG. 5, the entire shell22a may be formed of a plastic having a low energy surface. Under somecircumstances, and as shown in FIG. 6, the Shell 22h may be formed ofmetal throughout-no plastic inner lining being provided. In this case,however, it is preferable that a seal or a tight iit be provided betweenthe wall sections of the insert and the inner wall of the shell 22b.

In order to facilitate the manufacture of the insert so that a widerrange 0f dimensional tolerances may be used, as shown in FIG. 7 theouter edges of the wall sections 30 and 32 may be tapered or featheredand the overall envelope diameter of the insert made slightly largerthan the internal diameter of the shell 22. With this construction, asthe insert 26a is pressed into the shell 22, the resilient edges of thewall sections are bent toward the rear and when the insert is in placethe inherent memory of the material from which the insert 26a is moldedcauses the walls t0 move toward their originally molded position therebyproviding a tight sealing ft between the wall sections and the innerwall 28 of the shell 22. I-f desired, this aspect of the invention maybe utilized by molding the insert 26 in the shape shown in FIG. 2 buthaving a slightly larger diameter than the internal diameter of theshell with which it is to be used. Prior to assembly of the insert 26into the tube, the outer edges of the insert are treated with a chemicalto render them soft and pliable during the insertion operation.

The insert 26 may be formed of any shape-retaining material, such, forexample, as metal but preferably it is molded of plastic. Accordingly,it may be formed of polyethylene, polypropylene, Teflon or othersuitable plastic which has suflicient strength to retain its shapeduring assembly and use and which occupies a relatively small totalvolume in the reservoir. Using polypropylene, it has been found that aninsert having the following dimensions has a volume about the same asthat of a grease follower replaced by the insert.

Inches Insert length 2.25 Insert diameter .213 Axial length f wall 32.125 Thickness of Wall 30 .025 Thickness of wall 32 .025

While the present invention has been described in connection withparticular embodiments thereof, it will be understood that those skilledin the art may make many changes and modifications without departingfrom the teachings of the present invention. Therefore, in the appended,claims it is intended to cover all such changes and modifications ascome within the true spirit and scope of this invention.

We claim:

1. An insert for disposition in a tubular ink reservoir member of a ballpoint pen to provide a generally serpentine capillary passagewayextending from one end of said tubular member which is open to theatmosphere to the other end of said tubular member which is connectedthrough a feed channel to a writing ball, said insert comprising amember having a plurality of parallel, transversely extending walls anda plurality of longitudinally extending spacer walls respectivelydisposed between adjacent ones of said transverse Walls,

said transverse walls having a shape generally complementary to saidtubular member and said spacer walls extending inwardly from themarginal edges of the adjacent transverse walls,

said transverse walls each being provided with an aperture locatedadjacent to one side of the two adjacent spacer walls, and

the apertures adjoining each of said spacer Walls being disposed onopposite sides thereof whereby ink placed in said reservoir occupies aserpentine passageway from the open end of which ink will not flow underthe force of gravity.

2. An insert according to claim 1 wherein said transverse walls aregenerally circular, and

said apertures are disposed at the edges of said transverse walls. 3. Aninsert according to claim 2 wherein said transverse walls are mutuallyparallel. 5 4. An insert according to claim 2 wherein said aperturesextend to approximately the center line of said insert and are in theshape of a 90-degree segment of a circle. 5. An insert according toclaim 1 wherein said spacer walls each lie in a radial plane, andsuccessive ones of said spacer Walls are displaced from one another byan angle of about 90-degrees. 6. An insert according to claim 1 whereinsaid insert is formed of a rigid plastic material.

7. An insert according to claim 1 wherein said insert is formed ofmetal.

8. An insert according to claim 2 wherein the peripheral edges of saidwalls dene a cylinder having a diameter slightly greater than theinternal diameter of said tubular member, and the peripheral edges ofsaid walls are flexible so as to deflect as said insert is pressed intosaid tubular member, whereby a tight tit is provided between the wallsof said insert and said tubular member.

References Cited UNITED STATES PATENTS 2,601,846 7/1952 Klegges 401-253FOREIGN PATENTS 935,473 2/1948 France. r 66,053 1/1956 France. 31,144,020 4/1957 France.

LAWRENCE CHARLES, Primary Examiner.

U.S. Cl. X.R. 401-230

